Table 3.

Dimensions of hydrated proton, small chemical molecules, and proteins

Molecule	Mw (g/mol)	XYZ dimensions (nm)a	Database accession number
Hydrated proton (H3O+)	19	0.1 (O-H) × 0.2 (H-H) × 0.2 (H-H)	13968-08-6 (CAS)
HEPES	238	0.5 × 1.0 × 0.3	7365-45-9 (CAS)
FM 4-64b	608	0.9 × 3.0 × 0.3
Human ANP	∼3 × 103	2.1 × 2.1 × 1.1	1ANP (PDB) (Cunningham et al., 1994)
GFP mutant	∼27 × 103	3.8 × 5.1 × 3.6	2EMO (PDB) (Palm et al., 1997)
Human prolactin	∼23 × 103	5.2 × 6.4 × 3.3	1RW5 (PDB) (Teilum et al., 2005)

O-H, Oxygen atom to hydrogen atom; H-H, between two hydrogen atoms; CAS, Chemical Abstracts Service numbers for small chemical molecules; PDB, Protein Data Bank numbers for proteins; ANP, atrial natriuretic peptide; GFP, green fluorescent protein.

^aXYZ dimensions of molecules were measured with a Pymol Molecular Graphics System.

^bThree-dimensional model of FM 4-64 was obtained with MDL ISIS/Draw (version 2.5) and a Pymol Molecular Graphics System.